Some Advice on How To Roll Correctly in Stinky Things
A little guide to dogs

Labrador checking the ground.

First, you check out the ground judiciously. Don't start as long as you're not certain wether this is the correct place.

Labrador rolling on the ground.

Then, you roll thoroughly in it and at some length.

Labrador getting on his paws.

At the end, you get back up on your paws normally because you have just done normal things and go on. That was easy, wasn't it? So it's your turn, have a try, and maybe you can win your master for the next roll-in?